```js
// /my-addon/register.js

import React from 'react';

import { useGlobals } from '@storybook/api';

export const Panel = () => {
  const [globals, updateGlobals] = useGlobals();

  const isActive = globals['my-param-key'] || false;

  return (
    <button onClick={() => updateGlobals({ ['my-param-key']: !isActive })}>
      {isActive ? 'Hide me!' : 'Show me!'}
    </button>
  );
};
```